1. Field of the Invention
This invention generally relates to various methods and equipment employed in training motorbike riders on how to safely ride a motorbike in a wide variety of conditions and more specifically to the use of special outrigger devices attached to the frame of the motorbike, which extend out from the frame and contact the ground and directly control the motorbike's lean angle as it goes through a corner.
The present invention consists of two structural frames or outriggers, attached to either side of the bike extending out for a few feet with a wheel at the end of the outriggers which is in contact with the ground until the lean angle of the bike exceeds 40 degrees. The position and angle between these outriggers and the bike can be incrementally controlled by the rider by means of a lever mounted on the handlebars and controlling the pressure inside two shock struts attached to both outriggers and to the bike.
2. Description of the Related Art
In the training of new motorbike riders, one of the hardest things for the novice to learn is how to set the correct lean angle of the bicycle and the rider's body, as it goes through a corner. When any vehicle goes around a curve, a centrifugal force is generated horizontally. This force is a function of the weight of the vehicle, the radius of the curve and the velocity of the vehicle itself.
In the case of 4-wheeled vehicles, the base created by the 4 wheels naturally generates a vertical balancing moment to counteract this horizontal force. Unlike 4-wheeled vehicles, motorbikes must be leaned over through an angle, to generate the correct balancing moment when they go around a corner. This balancing moment is defined by the weight of the bike plus rider, acting at the combined center of gravity, multiplied by the distance between a vertical line through the combined center of gravity and another vertical line through the road contact point of the wheels. Thus at higher and higher cornering speeds, the rider must lean the bike over by increasingly greater angles to balance the increasing horizontal force.
If the bike is leaned too little or leaned too much it can quickly generate unstable driving conditions which can make the bike slide out from under the rider or the bike can topple to the high side (away from the corner). Learning the correct lean angle is therefore a skill that must be quickly learned by the novice. This degree of angle can at first, seem very threatening to the novice or trainee rider and so there is a need for a device to control the lean angle by some other means that is under the direct control of the rider.
In an earlier invention identified above, I describe a set of outriggers which can be installed on a motorbike and which allow the direct control of the lean angle of the bike by the rider. This earlier invention utilizes an air compressor and pneumatic valve to control the flow of hydraulic fluid through a bypass system.
The present invention is a simplified version of that earlier invention and incorporates a number of new embodiments that are improvements over the earlier application.
There are a number of existing designs in the art where extra structures and wheels are added to a basic 2-wheeled bike. For instance, sidecars have been in use for some time and are added to transport another passenger or to carry payloads. Sidecars are fixed rigidly to the bike frame and although they add lateral stability to the bike, this is a secondary factor. Further, a sidecar is only added to one side of the bike unlike the present invention, which adds a structure to both sides of the bike, and in an adjustable, controllable manner.
In the case of a motorbike and side-car, the sidecar supplies a lot of the stability that is missing in a two wheeled vehicle and creates a much more stable platform for the rider. However the sidecar is fixed to the side of the bicycle and does not move or rotate relative to the bike as the bike goes through a comer. The vertical center of gravity of the bike/side-car combination lies between the 3 wheels and so creates a moment (weight times distance) that counteracts the induced centrifugal force and subsequent moment created in the horizontal direction as the bike/side-car goes through a corner at speed. Also, unlike the present invention, the sidecar does not assist in the training of a bike rider who is learning to ride a bike with two wheels round a corner. As the rider is going through turns and corners on a 2-wheeled bike, he must learn how much to lean the bike as he goes through the corner.
Further, a bike with side-car is designed to be a freestanding system while the present invention applied to a 2 wheeled bike will allow the bike to lean over to either side. In the case of a bike plus side-car the bike cannot be leaned through corners, as the 3 wheels contacting the road act as a stable platform and lateral centrifugal forces are usually not sufficient to raise the side-car wheel off the ground, which would allow the bike to lean. This is especially true if a passenger is sitting in the sidecar or a payload is being carried.
Training wheels are also known in the art and can be used on a motorbike but they are generally rigidly fixed to the bike frame. While the bike is driven, they are used to limit lean angle of the bike to the angle, which is preset, before they contact the ground. They do not include any of the control or incremental training features of the present invention.
Also known in the art is the BMW (Bavarian Motor Works) design of outriggers, which are attached to the bike frame similar to the present invention. However, they are also positioned in a fixed relation to the bike frame, with wheels attached to the ends of each outrigger, which have a space between both of the wheels and the ground while the bike is moving in a straight line. When the bike is leaned over sufficiently in a corner, one of the outrigger wheels touches the ground and so limits the amount of lean.
A shock absorber is also used in the BMW design but only to reduce the impact forces in the case of a sudden lean that allows the outrigger wheel to hit hard on the road or track surface. This BMW device is designed mainly to measure wet weather traction forces on different types of tires. It has no capacity to allow incremental lean angle changes to the system and can not be used for quick turn and steep lean angle tests as can be done by the present invention.
The BMW bike outriggers could high-side the rider in a corner, as they do not maintain close contact between the outrigger wheels and the road, as in the present invention.
The definition of `high-side` as used in the disclosure is the action of a two-wheeled bike going through a comer and the front or rear wheel (or both) slips away from the cornering center then suddenly re-grips the road surface. This sudden re-grip can generate a large reaction force which acts to rotate the bike towards the vertical axis and which can be sufficiently strong to throw the rider off the bike.
The definition of `low-side` as used in the disclosure is the action of a two-wheeled bike going through a corner and the front or rear wheel (or both) slips away from the cornering center, causing the bike to fall down.
The definition of lean angle is the angle between a line perpendicular to the ground and the bike's vertical axis, as the bike leans over during a turn.
Apart from the inventor's earlier invention described herein, there is nothing in the prior art that allows the rider to overcome his fears in the manner of the present invention. The performance of the present invention can also be easily adjusted by changing orifice sizes in the hydraulic cylinders, which control the force required to change the lean angle for the rider. Thus control features of the invention can be changed to match the rider's confidence level as he improves his skills.
This natural fear that occurs when a novice is learning to ride a motorbike when turning into a comer is very real and must be overcome for the rider to become skilled at handling a bike under a wide variety of road conditions.
To traverse a right hand corner for example, the bike handlebars must first be turned to the left, away from the corner. This causes the bike to fall or lean to the right, due to centrifugal force generated on the bike and acting in a direction away from the center of rotation. Thus as the bike leans to the right, the front wheel automatically turns around to the right and helps to set the cornering radius of the bike and the bike's lean angle, as it goes around the right hand corner.
Since the bike has two wheels, it must be leaned into the corner deliberately by the rider, to offset the centrifugal force, which is trying to overturn the bike to the left. The tighter the radius of turn and the higher the road speed, the more that the bike must be leaned over, in some cases as much as 40 or 50 degrees from vertical. For most novice riders, there is a natural fear of leaning the bike too far, as this action appears to bring the bike and their body dangerously close to the ground.
There is also a fear of causing the bike to fall down or in the act of leaning far enough to make a turn, impacting some structural parts of the bike against the ground such as the footrest or oil pan. If this impact occurs, then weight is transferred off the wheels to the footrest for instance and the tires can loose traction causing the bike to fall over to the right, which may trap the rider's leg against the ground.
There is also the danger of a bike being leaned into a corner too much, causing the rear or front tire to slip and turn the bike further into the corner. The rear or front tire may then re-grip the road surface, creating a very strong force, which tries to straighten the bike up, and which can `high-side` the rider.
Another natural fear exists for the rider, of trying to avoid an obstacle in front of the bike and quickly turning the bike to either side, and so causing it to fall over. This fear is of course enhanced in any reduced traction conditions such as in rain, in mud or in gravel or on an oil spill.
Because of the nature of the dynamic forces acting on a motorbike as it goes through a corner at speed, and the inability of the bike's 2-wheeled structure, to counteract these forces, it is necessary for the rider to learn to balance these forces by leaning the bike and his body towards or into the corner. If not done correctly there is a considerable risk of the bike's tires loosing traction on the road or track surfaces allowing the bike to go into a skid and `high-siding` or `low-siding` the rider.
Leaning one's body with a bike into a corner nins counter to all basic instincts for the rider's safety, as the preference is to maintain the body in a position close to vertical. To efficiently ride and maneuver a bike the rider must learn to lean his body with the bike to a quite alarming extent and overcome this strong survival instinct,
The present invention is designed to teach the rider how to overcome this instinct. and lean through a corner correctly at different speeds and corner radii and so allows him to gain confidence in his riding skills while eliminating many of the dangers described herein. The invention also allows the rider to overcome the fear of leaning his body over with the bike in a comer instead of trying to maintain his body in an upright position, which requires leaning the bike further over than is necessary.
This has the advantage of less bike lean angle in a turn hence better use of the correct tire surface, which creates a better traction situation. It also requires less work from the rider, as he does not have to force the wheel over to get the correct lean angle; instead he uses his body to work with the bike to get the best lean angle. Another advantage of this correct lean angle is that in an accident situation, the rider can respond faster to the situation and turn the bike more quickly and so avoid a collision.
It is very important for the rider to learn to set the correct lean angle and hence turn radius, at the start of the turn through a corner as quickly as possible so corrections are kept to a minimum. Each correction made through a turn creates a degree of instability of the bike and rider with a resultant reduction in traction. By overcoming the rider's fear of leaning the bike quickly and through steep lean angles, this allows the rider to quickly set the correct lean angle and so go through the corner in the best and safest possible manner.
It is important that the rider learns how to lean a hike in a corner, become familiar with traction limits while cornering and to be able to safely turn quickly to avoid accidents. In accident avoidance at high speed bike riders must be able to quickly lean the bike to either side to get around objects in the road or track. The faster one approaches a turn on a bike the further one has to lean the bike over to go through the turn.
More than 50% of bike street accidents are caused by motorists turning their cars towards the left in front of a bike going the other way. If the rider is afraid of quick turns his only choice is to try to brake to avoid the accident which often is not enough. Similarly with road hazards and items falling off a truck or van which fall into the road in front of the bike, requiring the need for speedy and evasive action.
Against all instinct when going through a corner in the wet under nower, if the rear wheel slips, the first impulse of the novice rider is the cut the throttle which causes the rear wheel to slip to the opposite side of the turn and once the wheel regrips the surface, the large sudden braking force can easily throw the rider off the bike tip into the air as the bike straightens up. The present invention trains the rider to correctly lean the bike into the corner thus minimizing the possibility of a slip. He is trained to maintain the throttle position despite side slin and So he can maintain the slin through the corner or in the extreme case induce a low side fall, which is a better alternative than a high side crash.
Unlike the limitations of the other inventions noted in the art, the present invention allows the rider to press and release a pressure bleed lever located on the handlebars, which releases air by opening a valve inside a bypass line from the top to the bottom of a control cylinder attached to the two structures, thus allowing the bike to lean further to the side in a controlled, incremental manner. When the lever is released, the rider feels a reassuring resistance to any further lean as the bike now continues to lean very slowly, as oil bleeds through the orifice hole inside the cylinder. Furthermore there is a maximum lean set in the invention, which ensures that no part of the bike can hit the ground This reassurance to the rider allows them to experiment with lean angles in turns with much greater confidence and so speeds up their training in this important skill.